Polymers are used extensively to make a variety of products which include blown and cast films, extruded sheets, injection molded articles, foams, blow molded articles, extruded pipe, monofilaments, fibers and nonwoven webs. Some polymers, such as polyolefins, are naturally hydrophobic, and for many uses this property is a disadvantage. There are a number of uses for polymers where their hydrophobic nature either limits their usefulness or requires some effort to modify the surface characteristics of the shaped articles made therefrom. By way of example, polyolefins, such as polyethylene and polypropylene, are used to manufacture polymeric fabrics which are employed in the construction of such disposable absorbent articles as diapers, feminine care products, incontinence products, training pants, wipes, and so forth. Such polymeric fabrics often are nonwoven webs prepared by, for example, such processes as melt-blowing, carding, coforming and spunbonding. Frequently, such polymeric fabrics need to be wettable by water or aqueous-based liquids. Wettability can be obtained by spraying or otherwise coating (i.e., surface treating or topically treating) the fabric with a surfactant solution during or after its formation, and then drying the web.
Water-absorbent articles, especially personal care absorbent articles, such as diapers, training pants, sanitary napkins and incontinence products, typically include at least one nonwoven polymeric fabric. As surge diaper layer (i.e. layer used under the liner and not in direct contact with skin), for example, the nonwoven fabric provides rapid acquisition, adequate retention, and efficient distribution of a fluid such as water or an aqueous solution. However, polyolefin nonwoven fabrics and other types of polymeric fabrics are normally hydrophobic and are water-repellent. Thus, to effectively absorb water the polymeric fabrics must be treated to become hydrophilic. In addition, it is desirable that the hydrophilic treatment promotes a dryer environment by reducing and controlling moisture dampness in an enclosed or occlusive environment as during diaper wear. Skin moisture is a major source of skin health problems associated with the use of diapers that do not effectively maintain a dry environment at the material/skin interface. Accordingly, there is a need to improve the hydrophilicity or wettability of fibers, nonwoven fabrics and other substrates and to impart superior absorbent functions to a diaper and, desirably, promote a dryer environment within a diaper, particularly to substrates in a diaper that will be used not in direct contact to the skin of a wearer.